In the broadest sense, our research objectives are to understand biological processes and phenomena in terms of physical mechanisms and to explore the adaptation of physical phenomena and techniques to problems in biology. The more specific goals and problems to which we are addressing ourselves in this proposal are the following: 1. The mechanisms of energy conversion and electron transfer in a protein-chlorophyll complex solubilized from a bacterial membrane and the characterization of the protein complex. Different physical techniques (e.g., EPR, optical techniques, electron microscopy, Mossbauer spectroscopy, etc.) and biochemical methods (e.g., immunological, amino acid composition and sequence determination, gel filtration, gel electrophoresis, etc.) are being used. 2. The application of the technique of fluctuation spectroscopy to biology. The two specific problems are: the determination of the molecular weight of DNA from eukaryotic cells and the determination of the kinetics and the cooperativity of conformational changes in polynucleotides. 3. The use of coherent light scattering to study aggregation processes of macromolecules with special emphasis on the investigation of crystallization mechanisms of proteins.